Impact of the Fe(III)-reducing bacteria Geobacter sulfurreducens and Shewanella oneidensis on the speciation of plutonium

Renshaw, Joanna C.; Law, Nicholas; Geissler, Andrea; Livens, Francis R.; Lloyd, Jonathan R.

doi:10.1007/s10533-009-9318-8

Cited by 38 publications

(32 citation statements)

References 14 publications

(24 reference statements)

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“…Pu interaction with EPS is likely to induce redox transformations and, as a result, changes in Pu speciation and mobility. Compared to the reduction of Pu(IV) to Pu(III) that was observed under anoxic conditions (26,28), facile Pu(V, VI) reduction to Pu(IV) is expected to occur under oxic conditions (25).…”

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confidence: 99%

“…can also solubilize solid Pu(IV)O 2(s) by reducing it to Pu(III) (24). Studies with the dissimilatory metal-reducing bacteria (DMRB) Geobacter metallireducens and Shewanella oneidensis reported the formation of inorganic Pu(IV) colloids after exposure to a mixture of Pu(V) and Pu(VI) under anoxic conditions (25) and the formation of Pu(III) in some cases (26)(27)(28). These laboratory studies demonstrate that Pu sorption to bacterial surfaces can be driven by a variety of mechanisms, including redox transformations, resulting in Pu products of different composition and stability.…”

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Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Boggs

Jiao

Dai

et al. 2016

Appl Environ Microbiol

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Safe and effective nuclear waste disposal, as well as accidental radionuclide releases, necessitates our understanding of the fate of radionuclides in the environment, including their interaction with microorganisms. We examined the sorption of Pu(IV) and Pu(V) to Pseudomonas sp. strain EPS-1W, an aerobic bacterium isolated from plutonium (Pu)-contaminated groundwater collected in the United States at the Nevada National Security Site (NNSS) in Nevada. We compared Pu sorption to cells with and without bound extracellular polymeric substances (EPS). Wild-type cells with intact EPS sorbed Pu(V) more effectively than cells with EPS removed. In contrast, cells with and without EPS showed the same sorption affinity for Pu(IV). In vitro experiments with extracted EPS revealed rapid reduction of Pu(V) to Pu(IV). Transmission electron microscopy indicated that 2-to 3-nm nanocrystalline Pu(IV)O 2 formed on cells equilibrated with high concentrations of Pu(IV) but not Pu(V). Thus, EPS, while facilitating Pu(V) reduction, inhibit the formation of nanocrystalline Pu(IV) precipitates. IMPORTANCEOur results indicate that EPS are an effective reductant for Pu(V) and sorbent for Pu(IV) and may impact Pu redox cycling and mobility in the environment. Additionally, the resulting Pu morphology associated with EPS will depend on the concentration and initial Pu oxidation state. While our results are not directly applicable to the Pu transport situation at the NNSS, the results suggest that, in general, stationary microorganisms and biofilms will tend to limit the migration of Pu and provide an important Pu retardation mechanism in the environment. In a broader sense, our results, along with a growing body of literature, highlight the important role of microorganisms as producers of redox-active organic ligands and therefore as modulators of radionuclide redox transformations and complexation in the subsurface.T he civil production of nuclear energy and military production of nuclear materials have resulted in an estimated worldwide inventory of over 2,000 metric tons of plutonium (Pu) (1). This inventory continues to increase at a rate of approximately 70 metric tons per year as a result of global nuclear energy production (2). Due to its long half-life (24,100 years for 239 Pu) and high radiotoxicity (3), Pu is an important driver in public health risk assessments for nuclear waste repositories and radiologically contaminated sites. However, predicting how Pu behaves in the environment and ultimately calculating its human health risk are limited by our understanding of the dominant biogeochemical processes controlling its behavior.The behavior of Pu in the environment is strongly dependent on its oxidation state and concentration. Among all the actinides, Pu has one of the most complex chemical, redox, and surface sorption behaviors. At low concentrations, Pu can exist as aqueous species in the III, IV, V, and/or VI oxidation states, all of which have different solubilities (4), mineral sorption affinities (5-7), and hence...

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Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Boggs

Jiao

Dai

et al. 2016

Appl Environ Microbiol

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“…reduction to Pu 3? has been reported before under anaerobic conditions by metal-reducing bacteria: Geobacter metallireducens GS15 and Shewanella oneidensis MR1 (Boukhalfa et al 2007), Geobacter sulfurreducens and Shewanella oneidensis (Renshaw et al 2009), and Clostridium sp. .…”

Section: Upgrading Ccbatch For Anaerobic Growthmentioning

confidence: 60%

Bacterial Pu(V) reduction in the absence and presence of Fe(III)–NTA: modeling and experimental approach

2011

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Plutonium (Pu), a key contaminant at sites associated with the manufacture of nuclear weapons and with nuclear-energy wastes, can be precipitated to "immobilized" plutonium phases in systems that promote bioreduction. Ferric iron (Fe(3+)) is often present in contaminated sites, and its bioreduction to ferrous iron (Fe(2+)) may be involved in the reduction of Pu to forms that precipitate. Alternately, Pu can be reduced directly by the bacteria. Besides Fe, contaminated sites often contain strong complexing ligands, such as nitrilotriacetic acid (NTA). We used biogeochemical modeling to interpret the experimental fate of Pu in the absence and presence of ferric iron (Fe(3+)) and NTA under anaerobic conditions. In all cases, Shewanella alga BrY (S. alga) reduced Pu(V)(PuO(2) (+)) to Pu(III), and experimental evidence indicates that Pu(III) precipitated as PuPO(4(am).) In the absence of Fe(3+) and NTA, reduction of PuO(2) (+) was directly biotic, but modeling simulations support that PuO(2) (+) reduction in the presence of Fe(3+) and NTA was due to an abiotic stepwise reduction of PuO(2) (+) to Pu(4+), followed by reduction of Pu(4+) to Pu(3+), both through biogenically produced Fe(2+). This means that PuO(2) (+) reduction was slowed by first having Fe(3+) reduced to Fe(2+). Modeling results also show that the degree of PuPO(4(am)) precipitation depends on the NTA concentration. While precipitation out-competes complexation when NTA is present at the same or lower concentration than Pu, excess NTA can prevent precipitation of PuPO(4(am)).

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“…Hodge et al (1973) observe that the biological behavior of uranium, thorium, and plutonium resemble that of ferric iron. Microbial reduction of Pu(VI), in some cases all the way to Pu(III), has been reported several times (Boukhalfa et al, 2007;Icopini et al, 2009;Livens et al, 2010;Panak and Nitsche, 2001;Renshaw et al, 2009). The case for neptunium is more complex; some microbes capable of reducing uranium and plutonium can reduce Np(V), but others cannot (Livens et al, 2010).…”

Section: Microbial and Humic Colloidsmentioning

confidence: 97%

Radioactivity, Geochemistry, and Health

Siegel

Bryan

2014

Treatise on Geochemistry

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Impact of the Fe(III)-reducing bacteria Geobacter sulfurreducens and Shewanella oneidensis on the speciation of plutonium

Abstract: Microbial bioreduction of radionuclides has been the subject of much recent interest,

Cited by 38 publications

References 14 publications

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Interactions of Plutonium with Pseudomonas sp. Strain EPS-1W and Its Extracellular Polymeric Substances

Bacterial Pu(V) reduction in the absence and presence of Fe(III)–NTA: modeling and experimental approach

Radioactivity, Geochemistry, and Health

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